"I continue to believe that the U.S. should consider assertive ways to end the atrocities committed against the Syrian people," Casey said.
But Army Gen.
"Syria today is not about choosing between two sides, but rather about choosing one among many sides," Dempsey wrote in a letter to Rep.
The alleged attack comes a year and a day after the president first declared that the use of chemical weapons would be a “red line” that would trigger a response from the U.S.
In June, the White House said it would provide "military assistance" to the rebels because it had concluded that the Syrian government had used lethal chemical weapons, charges denied by the Syrian authorities. But more than two months later, Syrian opposition leaders say they have yet to receive any U.S. weapons or ammunition, and haven't even been told what to expect or when to expect it.
U.S. agencies have so far provided only nonlethal aid to the rebels, such as mobile radios, in addition to $1 billion in humanitarian assistance. But the slow roll-out of military help is seen as another sign of the administration's reluctance to become more deeply involved.
White House Spokesman Josh Earnest on Wednesday avoided discussion of whether the alleged chemical attack outside the Syrian capital, Damascus, in which opposition activists accuse the government of killing hundreds of civilians -- constituted a crossing of the administration's red line.
Defending administration policy, he cited condemnation from other world leaders and the effect of economic sanctions as evidence that Assad's government was feeling pressure. Still, he acknowledged that the U.S. action "has not resulted in the outcome that we would like to see, which is Assad being completely removed from power."
The White House pointed to the
Administration officials tried to pressure Russia to support a United Nations investigation of the alleged attack Wednesday.
“Even some people who may disagree with us on some aspects of our policy related to Syria should be able to agree that the use of chemical weapons is completely unacceptable,” Earnest said.
The allegations of chemical weapons use remain uncorroborated, and Syrian authorities have labeled the charge a fabrication.